This report assembles information on estimates of the willingness to pay for changes in health risks. The goal of this review is to provide enough detail on how each study was conducted to allow the reader to have a true feel for the different willingness-to-pay estimates and their applicability to different policy questions. Other reviews do not give the range of estimates found by each study as well as the authors' rationale for selecting one estimate as better than another. The qualifications that the authors present, along with their estimates and the context in which they are estimated, are important for interpreting the policy usefulness of these numbers. Most reviews give these considerations a very cursory treatment and when the estimates actually appear in policy assessments, the qualifications tend to disappear entirely. The result has been inappropriate application of the estimates and, even where applied properly, the level of confidence policy makers should have in the numbers has generally been left unstated. The purpose of this document is to compile the available empirical estimates and documentation in one reference source, present a critical discussion of the estimates, and discuss their usefulness in policy assessment. Many questions are raised for which adequate empirical studies are not available, but which point to useful avenues for future research.